Why? What gave archosaurs the edge as large predators at this time, and therapsids the edge as smaller ones? Animatronic dinosaur for sale Frankly, I am not sure. Both seem to have had heightened metabolic rates and fur or feather insulation. Some suggest that the archosaurs were better at conserving water and came to dominate the drier highlands. t But members of the therapsid-mammal group show no problems in dominating deserts today, and the archosaurs made it in the wet lowlands of the Triassic. Both groups developed more erect limbs at about the same pace, limbs that worked under the body like a bird’s or dog’s, rather than out to the side as in sprawling lizards. The big thecodonts did develop a special and highly developed form of the fully erect gait that therapsids never did match. Why the erect gait may be better than a sprawling one for big active animals has only just been explained. While erect gaits look more structurally and energetically efficient, Robert Bakker found that sprawling-limbed lizards running on treadmills are just as energy-thrifty as erect limbed animals.2 And as will be explained in Chapter 6, lizards are faster than small hopping dinosaurs. The key to understanding the advantage of an erect gait was offered by David Carrier in 1987. He pointed out that the assrmmetrical, sideways body action of running, sprawling- limbed animals directly fnhrbirs the operation of the lungs. Hardly able to breathe when moving swiftly, sprawling animals cannot go fast for long. Some lizards stop for brief moments even when running to escape in order to get a breath or two in. Erectgait animals, tall and with their limbs directly beneath their bodies, flex their trunks in a vertical action that helps the lungs work faster. Able to get more gen when they run, they can run for much longer. realistic dinosaur costume.
Perhaps the chief advantage enjoyed by thecodonts centered around their big, slashing attack jaws. These may have made them better big-game hunters, while the more precise cutting teeth of therapsids were more suitable for smaller prey.